Immunoexpression of HER2 pathway related markers in HER2 invasive breast carcinomas treated with trastuzumab

Purpose: We evaluated the immunoexpression of potential markers involved in the HER2 pathway in invasive breast carcinoma with HER2 amplification treated with trastuzumab.Methods: Samples of ninety patients diagnosed and treated at two public Brazilian hospitals with overexpressed invasive carcinoma between 2009 and 2018 were included. Several markers (Bcl-2, CDK4, cyclin D1, EGFR, IGF1, IGF-1R, MDM2, MUC4, p16, p21, p27, p53, PTEN, RA, TNF alpha, and VEGF) were immune analyzed in the tumor by immunohistochemistry and then correlated with clinicopathological variables.Results: Tumor sample expression results determined potential markers of good prognosis with statistically significant values: cyclin D1 with a nuclear grade, and recurrence; IGF-1 with tumor size, and death; p16 with a response after treatment; PTEN with a response after treatment, and death. Markers of poor prognosis: p53 with histological, and nuclear grade; IGF-1R with a compromised lymph node. The treatment resistance rate after trastuzumab was 40%; the overall survival was 4.13 years (95% CI 5.1-12.5) and the disease-free survival was 3.6 years (95% CI 5.1-13.1).Conclusions: The tumor samples profile demonstrated that cyclin D1, IGF-1, p16, and PTEN presented the potential for a good prognosis and p53 and IGF-1R for worse.